Polarizing elements are generally manufactured by adsorbing and orienting iodine, which is a dichroism pigment, or a dichroism dye onto and into a polyvinyl alcohol resin film. Polarizing plates are made by adhering a protection film made of triacetylcellulose, etc. on at least one surface of these polarizing elements via an adhesive layer to be used for a liquid crystal display, etc. Polarizing plates which use iodine as a dichroism pigment are referred to as iodic polarizing plates, while polarizing plates which use a dichroism dye as a dichroism pigment are referred to as dye polarizing plates. Of these plates, dye polarizing plates are characterized in that they have high heat resistance, high humidity, heat durability, and high stability, and have high color selectivity due to formulation thereof, while dye polarizing plates are problematic in that the transmittance thereof is lower than that of iodic polarizing plates having the same degree of polarization, that is, the contrast is low. Therefore, a dye polarizing plate is desired which maintains high durability, and has various color selectivities, high polarization properties and higher transmittance. However, even such dye polarizing plates with various color selectivities have up until now had polarizing elements that express a yellow tinge when the dye polarizing plate is arranged in parallel with the absorption axes while indicating white. When manufacturing a polarizing plate with a softened yellow tinge expressed when arranged in parallel in order to improve this yellow tinge when arranged in parallel, the polarizing element is problematic in that it expresses blue when arranged orthogonally to the absorption axes while indicating black. In particular, it is difficult to obtain a high-grade white polarizing plate, commonly referred to as “Paper White” polarizing plate. It is necessary for an achromatic polarizing plate to be independent of any wavelength when positioned in parallel or orthogonal, but have substantially specific transmittance, with such a polarizing plate having been impossible to obtain until now. The reason why the color in the parallel position is different from the orthogonal position is that, even if a dichroism pigment is used as the polarizing element, wavelength dependence is not the same in the parallel position and the orthogonal position; particularly, the transmittance at each wavelength is not specific, and further, the dichroism is not specific. Here, according to the explanation regarding one example of an iodic polarizing plate, a polyvinyl alcohol (hereinafter, abbreviated as PVA) is defined as a substrate; further, generally speaking, when iodine is used as a dichroism pigment, the iodic polarizing plate mainly absorbs at 480 nm to 600 nm. The absorption at 480 nm is said to be due to a polyiodine I3− and PVA complex, while the absorption at 600 nm is due to a polyiodine I5− and PVA complex. With respect to the degree of polarization (dichroism) based on each wavelength, the degree of polarization (dichroic ratio) based on the polyiodine I5− and PVA complex is higher than the degree of polarization (dichroism) based on the polyiodine I3− and PVA complex. This means that, when the transmittance is tried to be fixed in the orthogonal position at each wavelength, the transmittance at 600 nm is higher than that of 480 nm in the parallel position, resulting in the phenomenon in which light in the parallel position exhibits a yellow tinge. In contrast, when the transmittance is tried to be fixed in the parallel position, the transmittance at 600 nm is lower than that at 480 nm in the orthogonal position, resulting in light in the orthogonal position expressing blue. Further, since there is no absorption due to the complex mainly based on 550 nm with high visibility, the color phase is difficult to control. In other words, since the degree of polarization (dichroic ratio) at each wavelength is not fixed, wavelength dependence is generated. Moreover, the color cannot be adjusted since the dichroism pigment is determined.
Accordingly, wavelength dependence in the parallel position is also different from the orthogonal position in azo compounds with a dichroism other than the iodic polarizing plate, such that almost no pigment exists that expresses the same color phase in the parallel position and the orthogonal position; moreover, even if such a pigment existed, the dichroism (polarization properties) thereof would be low. Depending on the kinds of azo compounds with dichroism, an azo compound having wavelength dependence quite different in the orthogonal position and the parallel position exists, for example, expressing yellow in the parallel position and blue in the orthogonal position; moreover, contrast between brightness and darkness of light is also generated by controlling the polarization in the orthogonal position and the parallel position, wherein, as color sensitivity is also different from person to person with respect to the contrast between brightness and darkness provided, color correction suitable for each contrast between brightness and darkness is required assuming that a color correction is made. Such a color correction can only be achieved when the transmittance at each wavelength is substantially specific in the respective parallel and orthogonal positions; specifically, a state in which there is no transmittance dependency at each wavelength at a specific value is required. Moreover, regarding the polarizing elements or polarizing plate, the specific transmittance dependency thereof should be simultaneously satisfied in the parallel position and the orthogonal position; further, the degree of polarization (dichroic ratio) at each wavelength should be specific in order to have high transmittance and high contrast. Even when only azo compound is applied to the polarizing elements, each wavelength dependence is different in the orthogonal position and parallel position. Moreover, when several compounds are formulated, the relation between the transmittance in the parallel position and the orthogonal position and the dichroic ratio be finely controlled. On the other hand, even if the relation between the transmittance in the parallel position and the orthogonal position and the dichroic ratio is finely controlled, and the transmittance can be made constant in each case, an achromatic polarizing plate with high transmittance and high contrast cannot be realized. In other words, an achromatic polarizing plate with a high degree of polarization or an achromatic polarizing plate with high transmittance cannot be achieved. From this, it has been found very difficult to obtain an achromatic polarizing plate with high transmittance and/or high contrast, such that an achromatic polarizing plate with a high degree of polarization or an achromatic polarizing plate with high transmittance cannot be achieved only by applying a dichroism pigment of three primary colors thereto. It is also very difficult to make the parallel position specific while simultaneously controlling high dichroism. Particularly, a high-grade white color cannot be expressed even when a different color is slightly mixed with a white color. Moreover, a white color in a bright state is particularly desired since it has high brightness and high sensitivity. Consequently, although a polarizing plate that expresses a high grade paper-like achromatic white in white display while further expressing an achromatic black color in black display is desired as a polarizing element, to date there has been no polarizing plate that expresses achromatic white in white display with a single body transmittance greater than or equal to 35%, expresses an achromatic black color in black display and, further, has a higher degree of polarization.